The present invention relates to a machine for the security printing of security papers comprising a paper sheet-feed device, a device for transferring the papers toward a printing unit, a device for transferring printed sheets toward a unit for checking the print quality and a unit for storing printed sheets.
It is already known practise to incorporate, by way of security elements, optically-varying images or the like in the form of a film, for example on bank cards or security papers, particularly banknotes, so as to prevent counterfeiting thereof or make counterfeiting more difficult. These images, which are often optically varying comprising either a hologram or a kinegram, have the feature of changing appearance depending on the angle from which they are viewed.
Such images may be applied by different methods. By way of example, mention may be made of the device described in document EP-A-O 441 596 (MOLINS), the noncontradictory content of which is incorporated by reference, which describes a method and device for the cold application of such an image to a banknote. According to this device, the paper, in the form of sheets, having undergone selective application of an adhesive ink at specific points corresponding to the printings of the notes, and having traveled past the ultraviolet-radiation drying device, passes into a unit for applying such an image carried by a ribbon, which is dispensed between a dispensing reel mounted in a first cassette and a take-up reel mounted in a second cassette. The travel of the ribbon is parallel to the movement of the paper.
In document EP-A-0 625 466 (DE LA RUE GIORI), the noncontradictory content of which is incorporated by reference, the optically varying images, also supported by a ribbon, are applied to specific points, the application unit comprising at least one applicator cylinder and cooperating with an impression cylinder between which cylinders the paper passes. The ribbon is mounted between two reels arranged in one sector of the applicator cylinder and the ribbon passes along a generatrix of said applicator cylinder at right angles to the path of the paper.
This type of apparatus is equipped with means making it possible to ensure that the application of optically varying images is perfectly in register with the desired position on the security paper. These apparatuses are theoretically intended for just one single type of printing of security elements, they are expensive and are therefore not suitable for limited runs or for runs of security papers in which perfect print quality is not required.
If there is a desire to apply two security elements to a security paper using different methods, it is necessary to have use of two apparatuses, each one specific to the type and method of application of the security element. Likewise, or if there is a desire to be able to print security designs on limited editions using different methods, it is necessary to have one apparatus per method.